Transmission system



Oct. 29, 1929, J, 1Q KUHN TRANSMISSION SYSTEM Filed July 2, 1923 slsneetsnet 2 ,/4 /5 i R E f# a ii 2 y 5# "JJ, .4 v

J. J. KUHN TnANsMI'ssIoN ssma v Y Filed July 2, 1925 @at 2g, 1929.

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Fatented. Get. 29, 15929 i erratas elw-ED Stems 1 retenir A' errer:

JOHN'J. KUHN, OF ELIZAB'ETH, NEW JEBSEY, ASS'IGNGR T O -WESTERN ELECTIIC COM-I PANY, ETCOBORATED, OF NEW YGRK, N. Y., A CORPORATION OF NEW 'YORK TR-ANSMISSION SYSTEM l Application mea my 2,1923. serial no. eeaess.

This invention relates toa transmission system wherein' music, speech or other signals broadcasted as guided' or ungulded waves with or Without carrier Waves are received,"

amplified land distributed'to head phones, loud speakers -or other receiving deviceslocated in the various apartments of an apartment house or hotel or in the various oflices or roomsot anv oice building, bank, factory or other buildino.

The invention contemplates a central receiving station at which radio frequenciesmodulated in accordancel with signals may be receivedand the signals detected therefrom, or eien'al-s such as speech or musicincoming lover a telephone circuit from a distant sta- Y tion, such as a speakers platform or a studio,

inav be received. The radio frequencies mav be ungui'ded such as those radiated througli tbe ether 4from a radio transmitter, or guided such as those transmitted over Wires. The signals, however obtained at the receivinr station, are ain'plilied and then distributed to various stations local to the central receiving station. 'Such distribution may be effected in various ways. For example, in a building ot several floors on each of which are a plurality ot' rocnis in each of Which-is locateda local Y'receiving device, conductors individual to each local receivermay eXte-nd'tlieretrom to tbecentral receiver; or tberemay be provide-d bus bars having, connected thereto subbus bars from which extend conductors individual to each of a plurality of local stationsserved thereby. There may be a set of subbus bars for each floor or portion thereof, or j for the rooms hav-ing the same relative position on tbe various floors. l

The individuel local station-s maisT be connerted permanentlv'to" the central receiving .station or connected tlier'eto under control of either tbe'central station or tbe local stations nlieneverservice is desired.

Should trouble develop on on individual line. sublets bars or main bus bars. tbe section on which there is trouble may be disconnected 'trom tbe svstem and a compensating tion until tlie section is cleared of tlie trouble.

The vom@ ofthe Sig-nais delivered u; the

local stations may be controlled simultaneousc ly from the central station or individually from either the central or local stations.

The invention further contemplates a rc ceiving s vstem wherein a plurality of radio frequencies ot dilerent Wave lengtliseacli modulated bv ditl'e'rent messaoes muv be received. amplified end distributed so as to be A available to the various local stations.

Y Permanent connections from each radio receiver to each' local station may be provided,

sotliat tbe local receiver mav be connected t0 any desired radio receiver at the will of the occunant of the individual room. Or mean-s may be provided at tbe central station Where- 4by the attendant upon request froin a local station may connect such local station to the desired radio receiver. In the latter case the number of vconductors extending from the central 'station to' the local stations is veryl materiallv reduced. l

In the case Where the connection of the local station to any desired radio receiver is under control of the central station attendant, each of the radio receivers and associated arrinlif ving, equipment may develop sufiicientp volume to supplv all of'tbe local stations or only' aportion thereof. In ease a radio receiver and its associated amplifying equinment can serve onlyvaportion of the local sol stations. only a total number of local ste- `v tions ren'resentine' tlie capacity of suoli equip ment sliouldbe connected thereto et the same time.

If the program beine received on a radio receiver 'of suoli limited capacity' is particu larlv rood more than tbe proper'nurnber of local stations mav desire to be connected thereto at the same time. To take care ot suolia contingency,T Where there is a Waiting" list for connection to a radio'recoiver ot limited' capacity. a si maling arrangement. is provided whereby when s, local station disconnects from such a radio receiversJ signal at the central station operates to notitv tlie etten-dant ofi that. tact. @ne of tlie local stations on the waiting list may thereupon loe con nected in place of tbe station svliicli discon nectcd. A

i In the drawings:

Fig. l shows diagrammatically a building equipped with' the signal receiving system whereinv the signals 'are distributed to the various rooms by sub-bus bars extending 'ver-j same location o n eachjloor. Fig. 2 shows an arrangement'similar to that of Fig. 1 but differing therefrom in that each set of sub-bus bars serves all rooms or, a portion thereof on the same floor.

Fig. 3 shows diagranunatically the central ticallv and each serving the rooms having the receiving and amplifying' circuits and` apparates.

Fig. 4 shows diagrammatically circuits and apparatus for distributing the ampliied received signals to the local stations, the connection to the central receiving apparatus .being controlled'at the localstations.

Fig. 5 shows diagrammatically a'distribut-f ing system wherein the volume of the signals delivered to each set of sub-bus bars is controlled from the .central station.

- F ig. 6 shows diagrammatically an arrangement for clearing trouble from the distributing system.

Fig. 7 shows diagrammatically a receiving and distributing system wherein radio vsignals of three different wave lengths are received and distributed.'

Fig. S show s diagrammatically 'a rotary l switching arrangement at the central station tor connecting a local station to ,any one of v the Central signal receiving sets.

Fig. 9 shows an arrangement whereby a local station mayV connect the local receiverdirectly to any oneof thecentral signal` reeeiring sets. I

Fig. 10 shows an. arrangement somewhat similar to that of Fig. 8 with the addition of means for regulating the volume of the re-l ceived signals. A

Fig. 1 represents a building l equippedV with a radio receiver, and circuits and apmain bus bars 7 (represented by a single line) which extends around the building, so that each of the sets of sub-hns bars 8 connected' thereto may serve rooms or apartments on the different oors located one above the other.

or apartments may e provided with a signal i building of any size and number or rooms receiving and distributingv system of the" character disclosed herein.'

The arrangement of Fig. 2 is similar to that shown in Figui, but differs therefrom principally in the manner of distributing the ampliied detected signals. The sets of main bus bars 7 extend vertically and each of the sets of sub-bus bars 8 serves all ofthe rooms or apartments on a floor.

The. radio receiver 4 and amplifier' `which are merely' indicated in Figs. 1 'and 2 are shown more in detail inv Fig. 3, wherein is shown switch means whereby the'radio receiver (indicated generally by 4) may be coupled to either an aerial antenna 3 or on a loop antenna 9 to receive radio signals and then deliver the detected signals to the coupled ampliier 5.

The antenna has in series therewith av switch 10, variable tuning condenser 11 and the primary of a coupling coil 12, whose secondary is connected by switch 13, in a tuned loop circuit including a variahlecondens'er '14 and a loading inductance 15. When the- 18 wherein the radio frequency waves modulated in accordance with signals interact witn the unmodulated carrier frequency waves to produce the signals.4 The signals so detected are amplified by a low frequency' amplifier 19.

The amplified audio signals pass through an impedance matching transformer 20 and areV available on the terminals 21 of a switch 22.

The amplifiers 16, 17 and 18 and the detector v18 may he lof any well known type, such, for example, as the usualthree electrode .space discharge tube amplifiers and detector'.

The impedance matching transformer 2O and switch v22'. couple the output circuit of the radio receiver 4 to the input circuit of the amplifier 5.

The amplifier 5 may be otany well known type, such for example, as the amplifier disclosed in U. S. patent to Colpitts No'. 1,123,292, February 16, 1915.

The output circuit ot the ampliiier 5 is coupled to an outgoing circuit having terminals 23.

By means of the switch 22, the input cir= cuit of the amplifier 5 may have coupled Y thereto a transmitter 24 or an incoming circuit 25. llhe transmitter 24 has in circuit therewith en impedance matching transformer 26.

yl"he incoming circuit 25, which may include an il ipedance matching transformer 27, may

extend to a distant telephone exchange or studio at vvhioh it terminates in a-j-ack 28. At the studio or telephone exchange, a transmitter similar to 24, with additional amplifierv stages if desired, may be connected-to the i distributed to the local stations.

Thus. by means of the apparatus and circuits yat the central receiving station broadcasted radio programs, programs distributed over Wires (incoming over circuit may be received and then distributed to the local stations; or the central station attendant may make announcements to or otherwise communicate with the local stations.v

Profframs of music, news, etc., broadcasted 'i by radio on different Wave lengths may be receivcd and distributed as will more fully here' inafter appear. y

Likewise by providing more incoming 'trunk circuits like circuit 25 an one of sevv i Y eral programs of'music, news, etc., transmitted overv Wiresv may be received and dis,- tribute'd. Y

Figi i .shows .the distributing system by Whichthe received signals amplified by amplifier 5 may be distributed -to the local stations. i j l l.

This distributing system comprises a pair o'fmain bus bars 30, and a plurality of pairs of subio-ushers 31 coupling the local stations to the main bus bars 30.

The terminals 32 of the main bus bars 30 iiiay'be connected to terminals 23 (Fig. 3)

of the outgoing circuit'froin amplifier 5.

Each pair of sub-bus bars 3l may be connected to the nia-in bus bars 30 by atWo pole double throw switch 33. Should the sub-bus bars 3l or any apparatus connected thereto become grounded or'short circuited or trouble of any other character develop. thereon the sub-bus bars'may be'disconnected from the distributing system and a balancing load 3i substituted there or by throwing the switch to its second position. This balancinglo'ad maintains the volume ot the signals constant,

so that there is no change in the signals delivcrcd to the other connected local stations. The sub-bus bars 3l. may have connected thereto an vimpedence A matching transformer 35,

The sub-thus bars may be terminated in rarious Ways at the local stations 'Where either loud speakersv or head phones or-'both il be provided.

Several different Ways. otterminating the l sub-bus bars 81 at the local stations are shown in Fig. 4. A

For example at local stations A and B, the sub-bus bars terminate injacks 36.

Station A is provided with a pairof head phones 37 connectedto a plug 38 for con nection to the jack. When the plug 38 is disconnected from the jack, a balancino" resistance load 39 is substituted for .the head phones.

Station B is provided'with a loud speaker 40 connected to a'pl'ug for connection to the jack. l-Vhen the plug is disconnected from for the loud speaker.

Station C is provided with a three contact I y throughA a three winding transformer. 43. i

- One Winding is connected tothe bus bars, a

jack 42 connected to the subsbus" bars 3l `the jack, a balancing load 4], is substituted l second Winding to the tip and ring contacts' of the -jack, and the third Winding to` the tip and sleeve contacts ofthe jack. Either a pair vot' head phones connected to the tip'vand ring contacts of'three contact plug'll or a loud speaker connected-to the tip and sleeve con- 'tacts of a three Contact plug 4 5 may be coupled to thehus bars. The impedance of either the head phones or the loud speaker and the bus bar circuit are properly matched by means of the transformer 13.

Station D is provided with a jack conviocnected to. the-busbars through a variable tap autotransformer 47 wherebythe volume of the signals delivered to the local station v may be regulated thereat. The presence of the autotransformer insures that the impedance of the bar bar circuit is not changed when the volume of the received signals is a changed. Either head phones or loud spcakl ers may beeinploved.

T .he jack 4 8 of station E is connected to the bus bar through a regulating rheostat IIO 49 by which the volume of the received signais may be varied at the station. The regu` iating rheostat 49 is so constructed and' connected in the-circuit that when the bridged resistance is increased the series resistance is decreased by the same aniounhand vice versa, whereby no change in. impedance of" the bus bar circuit results. Either head phones or loud speakers may he employed.

Station F is provided with a ieri: 50 corr nected to the bus bars through a simple rhebf` stat 51 :tor regulating the volume ofthe re* paired signals. Either head phones or loudA speaker he employed.

Station G is provided with tivo jaclfsl and 5G with a fixed resistance 5l connected permanently iii circuit with the latter. 'A' loud speaker may be connected to iaclr a02 and a pair of head phones to 3fach 5G. The' resistance 5l serves to reduce the volume of the signals delivered` to the connected head phones. p

While for purpose of illustration diierent forms of the local station terminating a pa-l Aratus are shown connected to the sub-bus ars 3l?, such is not ordinarily the practice for a commercial lsystem wherein probably all local stations would be provided with the same form of terminating apparatus. y

Fig. 5 shows another forni 'of connecting apparatus bet-Ween the main bus bars andthe local stations. Thus the'main bus bars 30 may be connected by switch 33 to a variable tap autotransformer 52.A The various pairs of sub-bus bars 31 are connected in multiple to the autotransformer 52, and each pair of subbus bars has associated therewith a switch -52? by which the associated sub-bus bars may be variably connected to the autotransformer v 52'. In this manner the central station-attend.- ant who may control the several switches 53 to separately regulate the volume of the signals delivered to the various Apairs of sub-bus bars.` v. The distributing system, as shownin Fig.

.6, may be provided with means by which the v centrall station 'attendant may readily clear the'system of trouble in any of the local station apparatus. For example should the con`V ductors' in the cord 53 connecting the loud speaker (or head phones) to the' plug become short circuited, the loud speaker at that particular station will be put ont of commission, and the volume of the signals received at the other local stations reduced very materially. In such a case it is very desirable that the central st ation attendant be able-to clear the trouvble quickly and easily.

`Each local station jack 54 may therefore be connected to the sub-bus bars through ,fuses 55 (or heat coils) which vwill not blow due to the passage therethrough of the usual signal currents.' The central 'station attendant upon being informed that there is trouble at one .of the local stations, may throw switch 56 and connect tothe bus bars current, from source 57, of sufficient strength to blow the fuses or heat coils at the station where the short circuit exists.' The fuses at other 'stations will not blow because of the high resistance (of the head phones or loud speaker) in series therewith.

Fig. 7 shows a signal receiving and distributing system wherein a plurality 'of dif- Y ferent radio frequencieseachgrnodulated by j diiierent messages are received and distribut- (loop or aerial), a radio receiver 4A, an am plitier 5A and associated apparatus which.

may be similar to that described in connecf tion with Fig. 3.

Each radio receiver may be tuned tot receive a diiierent Wave length.

Severalditerent Ways of distributing the different detected messages may be e1nployed,.

as' indicated in Fig. 7

`The output from the several amplifiers is delivered to a setV of main bus, bars 60, 61,

62 and 63,.bus bar 60 being common to the several amplifiers and` each of the others being individual to an amplilier. i

Connection of the local stations t-'o the receiving sets may be controlled in several different Ways by the central station attendant.

Thus there may be provided at the central V `Jacks 65, 66 and 67 are connected tothe main bus bars so that there is available on each of lthese jacks the particular message delivered to the associated bus bars.

Connection of the jack 64. to the bus bar i jacks 65, 66 and 67 is effec-ted by means of twin plugs-, 70, '7l and 72, the plugs of which are spaced dil'erent' distances apart corresponding to the spacing of the jacks which are to be' connected thereby.

- In order to effect a saving in the cost of the central station receiving equipment the am# plifiers 535", and 5 may be designed to supply outputs of dierent values. Thus if the signal receiving anddistributingsystem is to supply a total of 300 local stations, amplier 5a may be designed to supply but 100 local stations, 5" to supply 200 local stations, and 5c to supply the entire 300 local stations. In order that ampliliers 5a and bjmay overloaded at any time, the central station is rovided with but 100 twin plugslike plug' O, 200 like plug 7l and with 300 like plug 72. Therefore, at no tin1e,'can more than 100 stations be connected to the receiving set A,

nor more than 200 to receiving set B al though all local stations may be connected to receiving'set C at the saine time.v

Should the central station attendant have not be more than the proper number of different kinds of plugs, it is possible that amplifiers 5a or 5b may be overloaded at some time due The conductor 7 3 terminates at the central station in a normally open contact of the jack 6d and at the local station in a normally closed contact of jack 69. vVYhle a plug is in jack 64 and the plug 75 (at local station) is in jack 69, the signal lamp- 74 is not lightedv for its circuit is open at the local station'.

The local station may be equipped with either head phones or a loud speaker connected to plug 7 5.

The central station operator, upon requestv from the local station communicated by telephone, speaking tube or otherwise, connects the local station line to the receiving set which is receivingv and supplying the prov gram speciiied by the local station.`

` the local station hasdisconnected and that another local station ma be connected to receiving set A in. place't ereof. The central station attendant may thereupon withdraw twin plug() from the jacks associated with the livlited signal lamp, which opens the circuitpt ereof, and insert such twin plug in the jacks of the local station Von the Waiting list. It such waiting local station is provided with a loud speaker it will usually be connected tothe jack thereat, so it will notibe necessary for the centralstation attendant to notify the local 'station that the connection has' been made. However, if the local station-is provided with head phones instead of a loud speaker the central station attendant will notify the local station at the time of mak ing the connection. l l c Instead ofy he plug jack arrangement of making connections to the lines to thelocal stations, other switching arrangements may be employed.

Thus, Fig. 8 shows a'switcn 76 located atV the central station andindividual to each local station. The movable contacts 77 of the switch are connected to the line conductors extending to the local station and terminating thereat in, a jack TS with which head phones or a loud speaker may he, connected by means of a plug {not shown). The switch 76 has stationary'contacts, one oi'which (con' tactfa'l) is connected to the common bus bar 6G and the others respectively to the bus bars individual to the. receivinar sets.'

A potentiometer, similar to that to he described in connection with Fig. 10, for regulating the volume of the signals may he socisted with the switch 76.

meaeoo adaptations.

to each of the local stations and terminating Fig. 9 shows the. main bus hars multipled thereat in liaclr's 80, 8l and 82'individual to.'

the receiving sets.

' F ig. l0 shows the main bus bars multipled to each of the local stations and terminating thereat in terminals of a switch 83.

The switch has contacts-S4, and 86 .respectively, individual to the receiving sets at the central station, and a cooperating rotatable Contact 87. Balancing resistances 88, 89 and 90 are connected, across the respective bus bar circuits through normally closed contacts of the switch. A potentiometer 91 for regulating the volume of the signals delivered to the head phones 92 (or loud speaker) is connected between the rotatable switch contact arm 87 and the common bus bar 60.

The local station by rotating the switch4 arm 'S7 may connect the local signal receiver 92 to any one of the central station receiving sets and simultaneously connect the poten Any of the various terminating arrange ments for single wave length reception an distribution .may be employed in` a system wherein a plurality of wave lengths are re ceived and distributed. Gbviously, inthe system wherein a plurality of wave lengths 'are received and distributed, the central station attendant may not only connect 'any of' the local stations to any of the receiving sets, but may also regulate separately the volume ofy the signals delivered to the various connectedlocal stations.

The invention set forth herein is of course susceptible of various other modifications and The invention claimed is:

l. A wave distributing 'system which comprises a radio receiving system, a transmitter and an incoming circuit over which signals are transmitted at a central point, an amplifier, switching means for connecting mitter or the incoming circuit'to the input circuit of the amplifier, a plurality of sul scribers stations comprising signal receivers at points at a distance .from said central point, a plurality of branch lines arranged to 'ne connected 'to certain of said receivers, a line connected to said amplifier, means for connecting and disconnecting said branch lines and said main line, and means associated with said main line for compensating for the disconnection off each branch line.

2. In a signal distributing system, a radio receiving over which signals are transmitted, an amplifier, switching means for connecting either th radioreceiving system, the trans leither 'the radio receiving system, the transsystem, a transmitter, 'an incoming v ,A

initier or the incoming circuit to the input circuit of the amplifier, a main line connected to said amplifier, a plurality of branch lines connected to said main line, a plurality of nected.

A3. A signal receiving system comprisinga radio receiver including a detector, an ampliier, an impedance matching device coupling the output circuit of the radio receiver to the L each pair of sub-bus bars, a plurality of local input circuit of the amplifier, a pair of main bus bars connected to the output circuit of the amplifier, a plurality of pairs of sub-bus bars connected to the main bus barsa switch to connect each pair of sub-bus bars to the main bus bars, a plurality of receivin devices connectible to each pair of sub-bus ars,

and a balancing load for each pair of sub bus bars connectible to the main bus bars by the associated switch.

4c. A signal receiving system comprising a radio receiver including a detector, an ampli- .Y i er, an impedance matching device coupling the output circuit of the vradio receiver to the input circuit of the amplier, a pair of main y bus bars connected to'the output circuit of the a'mpliier, a plurality of pairs of sub-bus bar s connected to the main us bars, a plurality of local stations for each pair of subbusbars, terminals at each local station connected to sub-bus bars therefor7 a signal'repliier, an impedance matching device cou-4 -ceiver 'at each local station, a balancingload' at each local station, and means to connect either the signal receiver or the balancing load across tle terminals.

A signal receiving system comprising a radio receiver includingv a detector, an ampling the output circuit of the radio receiver to the input circuit of the amplier, a pair of main bus bars connected to the output circuit of the amplifier, a plurality or' pairs of sub'- lius bars connected to the main bus bars, a plurality of local stations 'for each pair of sub-bus bars, terminals at eacli local station connected to sub-bus bars therefor, a signal receiver at each local station, a balancing load normally bridged across the terminals at each local station, and means to simultaneously connect the signal receiver across the terminals and disconnect tliebalancing load from bridged relation thereto.

6. i signal receiving system comprising a radio receiver including a detector, an amplifier, an impedance matching device coupling the output circuit of tlie radio receiver to tlie input circuit ot tlie amplifier, a pair of main bus bars connected to the output circuit of the WS v` l i `1,733,609

7; A signal receiving system comprising a v radio receiver including a detector, an ampliier, a pair of main bus bars connected to the output circuit of the amplifier, a plurality of airs of sub-bus bars, a balancing load for eac pair of sub-bus bars, a switch to connect either the balancinfr load or the corresponding pair of sub-busiars to the main bus bars, a plurality'of signal receivers connectible to stations for each pair of sub-bus bars, ter- 'minals at eacli local station connected tothe signal receiver or the balancing load across the terminals. Y

8. A signal receiving system comprising a radio receiver including a detector, a transmitter, an incoming. circuit over which sig-` nals are transmitted, an amplifier, means to connect said amplifier selectively to tlie de tector, the transmitter and the incoming circuit, a pair of main bus bars connected to the output circuit o tlie amplifier, a plurality of airs of sub-bus bars connected to the main us bars, a plurality of local stations for each Ypair of sub-bus bars, two signal receiversof different impedances for each local station, terminals at the localstaticn, means to connect either signal receiver tothe terminals, and impedance matching means connecting' the terminalsto the corresponding pair of sulo# bus bars.

9. Asignal receiving system comprising a radio receiver includingV a detector, a transmitter, an incon'iinff circuit over which sig nals are transmitte an amplifier, means 'to connect said amplifier selectively to the de' tector, the transmitter and the incoming cir cuit, ay pair of main bus bars connected to the output circuit of the aniplier, a plurality or" pairs of sub-bus bars connected to the main bus bars, a plurality of signal receivers con-v nected to eacli pair ot sublnis bars, and means associated with each signal receiver to regulate l the strength. of tlie signals delivered thereto.

10. A signal receiving system comprising a radio receiver including a detector, an ampli- -`-1,'zas,ao9 1 nal receiver to regulate the strength of the received signals and to maintain the sub-bus bar circuit impedance termination constant thereat.

5 In witne`ss whereof,1 hereunto subscribe my name this 27 'th day of June, A. D., 1923.

JOHN J. KUHN. 

